Laboratory Yields and Process Stream Compositions from E-Mill and Dry-Grind Corn Processes Using a Granular Starch Hydrolyzing Enzyme

In dry-grind corn processing, the whole kernel is fermented to produce ethanol and distillers dried grains with solubles (DDGS); the E-Mill process was developed to generate coproducts in addition to DDGS. Compositions of thin stillage and wet grains obtained from the E-Mill process will be different from the dry-grind process. Knowledge of thin stillage compositions will provide information to improve coproducts from both processes. Laboratory dry-grind and E-Mill processes that used granular starch hydrolyzing enzymes (GSHE) were compared and process yields determined. Two methods, centrifugation and screening, were used to produce thin stillage and wet grains from the laboratory processes. Compositions of process streams were determined. In the dry-grind process using GSHE, solids contents of beer, whole stillage, and wet grains were higher compared to the same fractions from the E-Mill process using GSHE. Solids contents of mash for both processes were similar. Total solids, soluble solids, and ash contents of thin stillage were similar for the two processes. Fat content of thin stillage from E-Mill was lower than that from the dry-grind process; protein content of E-Mill thin stillage was higher than that from dry-grind thin stillage. Removal of germ and fiber before fermentation changed composition of thin stillage from the E-Mill process. The screening method produced higher thin stillage and lower wet grains yields than using a centrifugation method. The screening method was less time consuming but resulted in limited wet grains material for additional analyses or processing. The centrifugation method of thin stillage separation removed more solids from thin stillage than the screening method.